Propeller



March 5, 1946. P. FQ A-CK'ETHM "2, 5, 7

PROPELLER Filed b s, 1940 s Sheets-'Shet i Q F901 ff/ncrrz-" rgmA March5, 1946. P, g E H 2,395,867

PROPELLER Filed May 3, 1940 3 Sheets-Sheet 2 I MIHHI a x I g! 3 v fiuzElia/rim;

March 5, 1946. P. F. HACKETHAL 2,395,867

7 PROPELLER Filed May 5. 1940 3 She'ets-Sheet 3 Flax? llllllllll 1710.ft'fi crrirflez.

STATES PATENT; OFFICE- PROPELLEB. I

Paul F. Hackcthal, Baltimore, Md, assignor to Everel PropellerCorporation, Baltimore, Md., a I corporation Maryland I Application May3, 1940, Serial No. 333,239

This invention relates to propellers, and more particularly hasreference to an automatic variable pitch propeller.

Most automatic variable pitch propellers are predicated upon the conceptof permitting the blade to move along the arc of a cone. This movementof course is in addition to the rotation of the propeller.

Movement along the cone arc effects a change in the pitch of thepropeller, and, in general, the propeller is so designed and constructedthat the pitch varies inversely with the density of the medium in whichthe propeller operates. For instance, in the case of an airplanepropeller, the blades will have the minimum pitch at sea level, but asthe plane operates at higher altitudes th pitch will be increased.

It is of course essential that there be a high sensitivity of thepropeller, insofar as its conically arcuate movement is concerned, andit is therefore obvious that frictional resistance of the moving partsshould -be maintained at a minimum.

propeller at maximum pitch, while the broken line indicates the positionof the propeller for minimum pitch.

Figure 2 is a side elevation of the propeller, with the solid lineindicating maximum pitch and the broken line indicating minimum pitch.

Figure 3 is a view, partly in plan and partly in section, j whichindicates the conically arcuate movement to effect a variation in thepitch of the blade.

Figure 4 is a vertical, longitudinal sectional view through the hub .ofthe propeller, showing in detail the mounting for-the blade.

Figure 5 is a sectional view, horizontally and longitudinally of thehub, and with various portions of the blade mounting in elevation.

Therefore, one of the principal objects'of the present invention is toprovide an automatic variable pitch propeller capable of moving aboutthe arc of a cone, and so constructedas to a low frictional resistance.7

Another object of my invention is to provide have ' an automaticvariable pitch propeller adapted to readily respond to changedconditions of or eration which render desirable a variation in the pitchof the propeller.

Yet another object of this invention is to provide an automatic variablepitch propeller of strong, but relatively light, construction which isdependable and eflicient in operation.-

To accomplish the above, and other important objects as will more fullyappear hereinafter, my inventionin general embraces the concept ofmounting a blade upon a rotative support and permitting movement of theblade with respect to the support to thereby vary the pitch the arrows.

In the accompanying drawings, there is dismodifications may be madetherein without dein a change in the pitch of the blade. stance, in themost forward position, indicated Figure 6 is a sectional view takenalongthe line 6-8-01 Figure 4 looking in the direction of Figure 7 is a'view' taken along the line 1-1 oi Figure 4 looking in the direction ofthe arrows. Flgure 8 is-a view taken along the line 8-8 of Figure 4looking in the directiono! the arrows.

Figure 9 isgzasview' in perspective of thesleeve,-- in which the bladeis mounted.

Flgureidis a view in perspective of a counterweight arm which maybe'used if necessary, and which is also designed to secure the bladeagainst rotation in the sleeve.

As indicated in. Figures 1, 2 and 3, the blades I are mounted in a hubdesignated generally 2 in such a manner that the blades may oscillateabout the longitudinal axis of the hub to describe the arc A of a conewhich has its apex in the hub adjacent the end of the blades. mostclearly shown in Figure 3, this movement-results Farinby the brokenlines in Figures 2 and 3, the blade is at minimum pitch, whereas in therearwardmost position, as indicated by the solid lines in these figures,the blade is at maximum pitch.

The ccnico-arcuate movement of the blade is attained by mounting theshank of the blade in a rotatable sleeve 8 so that the longitudinal axisof the blade isangularly disposed to the axis of oscillation of thesleeve. The resulting conlcoarcuate movement of the blade can be readilyvisualized by observing Figure 9 and assuming propeller clamping uponthe slotted cufi? 3D, as best shown that the sleeve 3 is oscillatedabout the axis 3a.

It will then be appreciated that the longitudinal axis In of the blade"will describe the arc of a cone which has its apex at the intersectionof 3a and la. p I Referring to the, mechanical construction of the huband mounting, it will he observed that the hub is centrally bored andprovided with I I splines} to register with corresponding splines uponthe usual crank shaft or drive shaft.

Opposite ends of the hub are recessed as indicated by'the numerals 5, inwhich recesses the sleeves 3 are fitted, so that the axis 3a of thesleeve 3 will coincide with the axis 2a of the hub 2. As shown in Figure6, channels 6 may be s drilled between the recesses 5 in order todecrease the weight oi. the hub, and two of the. channels 6 may be screwthreaded, as to, for the purpose of receiving balance weights. Suchbalance weights may be in the vlorrn of plugs I which, upon properpositioning-in the threaded channel,

may be anchored in suchpositions by means of a I slot and screw la, asbest shown in Figure 4.

Referring more particularly to Figure 9, the

sleeve 3 is made up of a cylindrical body section 95 3A and a flange 33at the inner end thereof. As best shown in Figure 4, the sections. 3Aand 3B of the sleeve are concentric with the recess 5. The sleeve 3 isbored, as at 3C, at an angle to the oscillation axis 3a of the sleeve toreceive the shank of the blade I. The outer end oi the sleeve 3 isreduced and slotted longitudinally to form a flexible cufl 3D concentricwith the bore 30.

The bore 30 in the sleeve 3 is threaded. and is adapted to receivecorersponding threads on the, blade shank. In assembling the blade andsleeve,

the blade is screwed into the sleeve and adjusted thereinso that theblade has the desired pitch.

The blade is then clamped in this position by means of a suitable clampencircling the slotted cufi 3D. When counterweights are employed, suchcounterweights may serve as'the clamp as disclosed herein. Thecounterweight 8 may be of the desired size and shape, and split topermit in Figure 10. A bolt and nut 9, or any other suitable means, maybe employed forsecurely clamping the counterweight to the slotted cufi3D. A flange 3E is formed upon the free end of the cufi 3D to preventany slipping of the counterweight or clamp therefrom. It will beappreciated 0! course that the clamp or counterweight will bind the cufi3D so tightly that rotation of the blade with respect to the sleeve 3 isprevented.

I The shank of the blade I is hollowand is adapted to receive a ballcage H. The ball cage II is provided with a flange i2 which is adaptedto fit into a corresponding recess at the end of the blade. The cage iiis provided with a central to recess l3 in which the ball it rests. Itwill be noted that the bottom of the recess i3 is conical to assist inthe centering oi the ball. The recess [3 is shouldered and provided withan annular groove, in order to receive a ball retaining mem- (as I herI! and a compressible retaining'ring- 16, re-

spectively. It will be noted that'the ball retaining member I5 iscentrally aperturedfto permit the projection of a portioni-theperimeter-of" the ball 14 therethroughx" v, t .Q IZA postijl isscrewed into a threaded aperture? centrally located in' thebase of therecess 5 so that it is adapted to contact the ball II when theQ'pi'opellerigassemmed., This. post and ball, in

assembly. I The inner surface f the sleeve 3 is provided with a pin 18which extends into one of the bores 6, orvpreferably 6a, and therebylimits the extent of oscillation of the blade with respect to the hub.It will of course be appreciated that it may be necessary to vary theshape-of the particular bore in which the pin projects in order to varythe limits of movement of the blade.

A single.combined radial and thrust bearin i9 is composed of balls l9a,inner race lilb, outer race I90, and bearing cage Hid. The inner racelllb is in frictional engagement with the cylindrical portion 3A of thesleeve 3 and bears against the flange 33 while the outer race is intriotional engagement with the wall of the recess 5.

The various elements are held in assembled position by means of a nut2!, which is threaded in recess 5, and which is provided with an annulargroove 2m to hold a packing element 22 and thereby retain lubricantWithin the recess.

The packing element 22 is of a type to reduce friction between the huband sleeve to a minimum andconsists of a plurality of flexible, chevronshaped rings 22a which fit the annular groove 2m and a pressure ring22?) positioned between the rings 22a and the outer ball race We. Onlythe inner peripheries of the rings 22a contact the 40 23 may be lockedin position by means of bolts 25 and, when so locked in mesh with theserrations of the hub, movement of the nut 2t is of course impossible.

While I have described my invention with reference to a propeller,particularly an aircraft propeller, it is of course obvious that theunderlying principle is applicable to other types of device, such as,for instance, ship propellers, fans, autogiro rotors, etc. I desireparticularly to point out that where I use the word "propeller in theclaims, such expression is to cover any type of blade adapted to rotatein a fluid and where it may be desired to change the pitch of the.blade.

While I have described a propeller which varies its pitch by virtue offorces acting directly on it, it will be appreciated that supplementarydevices may be employed to facilitate the variation of the pitch.

While I have shown and described the preferred embodiment of myinvention, I wish it to be understood that I do not confine myself tothe precise details of construction herein set forth by way ofillustration, as, it is apparent that many changes and variations may bemade therein, by

those skilled in the art, withoutdeparting from the spirit of theinvention, or-eirceedingthe scope I of the appended claims.

I claim I i. Anadjustable variable pitch propeller comprising a hubmounted upon a drive shaft, said -hub being provided with a radialrecess, a propeller blade mounted in a sleeve, said sleeve being freelyrotatably mounted in said recess, and beark ing means adapted todetermine the innermost sbciflti niyviththe other securing me ns. Serve7 position of the sleeve and eliminate slack in the propeller assembly,said bearing means comprising an adjustable element mounted in thebottom of said radial recess, said element being provided with a bearingsurface adjacent the sleeve,.and an anti-friction bearing disposedwithin said sleeve and cooperating with said bearing surface.

2. An adjustable variable pitch propeller as set forth in claim 1wherein the bearing means lies inthe axis of rotation of the sleeve.

3. An adjustable variable pitch propeller as set forth in claim 1wherein the propeller blade shank has a conical recess disposed withinsaid shank, the axis of said conical recess lying within the propellerblade axis, and said anti-friction bearing being detachabl; disposedwithin said recess. v

4. An adjustable variable pitch propeller comprising a hub for mountingupon a drive shaft, said hub being provided with a radial recess, apropeller blade, a sleeve for said propeller blade having a cylindricalexternal surface and a peripheral outwardly extending flange at theinner end thereof concentric with the external surface of the sleeve,bearing means cooperating with the external surface of the sleeve andthe flange and" with the wall of the recess for mounting the-sleeve in,the recess, said sleeve having a cylindrical blade-shank-receivingsocket formed therein,the

6. An adjustable variable pitch propeller com-.

prising a hub for mounting upon a drive shaft. said hub being providedwith a radial recess, a

propeller blade, a sleeve for said propeller blade socket bore, saidpropeller blade having a shank axis of which is inclined to that of thesleeve and recess, an axial cuif-likeflange extending from the outer endof the sleeve coaxiall of the bladeshank-receiving socket and having abore forming a continuation of the socket bore, said propeller bladehaving a shank mounted in said socket and cuff-like flange with its axisaligned with the axis of said socket, and additional hearing meansadapted to determine the innermost position of the sleeve and eliminateslack-in the propeller assembly, said additional bearing meanscomprising an adjustable element mounted in the bottom of said radialrecess, said element being provided with a bearing surface adjacent thesleeve, and an anti-friction bearing disposed within said sleeve andcooperating with said bearing surface. v

5. An adjustable variable pitch propeller comprising a hub for mountingupon a drive shaft,

said hub being provided with a-radial recess, a propeller blade, asleeve for said propeller blade having a cylindrical external surfaceand a pcripheral outwardly extending fiangeat the inner end thereofconcentric with the external surface forming a continuation of thesocket bore, said' propeller blade having a shank mounted in said socketand cuff-like flange with its axis aligned with the axis of said socket,and additional hearing means adapted to determine the innermost positionof the sleeve and eliminate slack in the propeller assembly, saidadditional bearing means comprising an adjustable element mounted in thebottom ofusaid radial recess, said element being provided with., abearing surface adjacent the sleeve, and an anti-friction bearingdisposed.

mounted in said-socket and cufi -like flange with its axis aligned withthe axis of said socket, and additional bearing means'adapted todetermine the innermost position of the sleeve and eliminate slack inthe propeller assembly, said additional bearing means comprising anadjustable element mounted in the bottom of said radial recess, saidelement being provided with a bearing surface adjacent the sleeve, andan anti-friction bearing disposed within said sleeve and cooperatingwith .said bearing surface, said propeller blade shank having a conicalrecess disposed within said shank, the axis of said conical recess lyingwithin the propeller blade axis and said anti-friction bearing beingdetachably disposed within said conical recess.

7. A propeller assembly comprising'a hub for mounting upon a driveshaft, said hub having a radial recess therein, apropeller blade, asleeve for the-blade, support means to mount the sleeve for coaxial freerotational movement within the recess, said sleeve having a blade shankrecelvinB' radial recess therein and a channel forming a longitudinalextension of said recess but disposed eccentrically with respect to theaxis thereof, a

propeller blade, a sleeve positioned about the shank of the blade,support'means for mounting the sleeve in the recess for coaxial freerotational movement with respect thereto, said sleeve being providedwitha blade shankreceiving bore. disposed at an angle to the axis ofthesleeve and recess thereby to effect a change in the pitchof the bladeupon rotation of said sleeve, a pin projecting from the inner end of thesleeve and selectively engageable with opposite walls of said channelfor determining maximum and minimum pitch positions of the blade, aweight member positioned in said channelandcapable of longi withinsaidsleeve and cooperating with said bearing surface, said additionalbearing means lying in the axis of rotation of the sleeve.

tudinal adjustment with respect thereto for balancing the propellerassembly, and means for frictionally engaging the weight member with thewall of said channel thereby to maintain an adjusted position of saidweight member.

9. An airscrew adapted to change. its pitch in accordance with theaerodynamic and centrifugal sleeve andcuff and likewise disposed -to theaxis of rotation of the hub, said sleeve being provided with a splitcufl angularly disposed with respect to the pivoting axis, of thesleeve, a blade shank adjustably mounted in said to the pivoting axis ofthe sleeve so that upon pivoting of the sleeve describes the arc-oi acone whose axis coincides with the pivoting axis of the sleeve, 9.counterweight clamped upon the cuff to fix the blade, the cuff and thecounterweight with respect to each other, said counterweight beingadjustable uponthe cuff to vary the effect of .thecounterweight.

10. An adjustable variable pitch air screw com prising a hub providedwith means for mounting at, an angle the gravity axis of the blade 0'!the sleeve in said recess, said last mentioned means including anadjustable element mounted in the 'of the, said element, and ananti-friction bearing interposed between said surface and a surface ofsaid sleeve.-

11. An adjustable variable pitch air screw comprising a hub providedwith means for mounting it upon a drive shaft for rotation about theaxis of the drive,shait, said hub being provided with a radial recess, ablade receiving sleeve pivotally mounted in said recess, a blade havingits shank mounted in said sleeve, cooperating means on said sleeve andhub for limiting outward movement ofsaid sleeve in said recess, andmeans for determining the innermost position of the .it upon a driveshaft for rotation about the axis of the drive shaft, said hub beingprovided with a radial recess, a blade receiving sleeve pivotallymounted in said recess, a blade having its shank mounted in said sleeve,cooperating means on said sleeve and hub for limiting outward movementof said sleeve in said recess, and means for determining the innermostposition of the sleeve in said recess and to eliminate axial movementsleeve.

sleeve in said recess and to eliminate axial movement of the sleeve insaid recess, said last mentioned means including an adjustable elementmounted in the recess upon the drive shaft mounting means, and alignedwith the pivoting axis of the sleeve, a bearing engaging surface uponsaid adjustable element, and an anti-friction bearing interposed betweensaid surface and a surface carried by the inner portion of said PAUL F.HACKETHAL.

recess and aligned with the pivoting axis sleeve, a bearing engagingsurface upon-

